JP2011233565A - Optical coupling device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase use efficiency of light emission with respect to an optical coupling device constituted in the form of one chip.SOLUTION: In a light receiving element region B1, a light receiving element 10 is formed, and a light emitting element 20 is formed on one principal surface of an Si substrate (semiconductor substrate) 11 in a light emitting element region B2. An insulating substrate 40 is bonded to the other principal surface of the Si substrate 11 with an insulating adhesive 41. Further, the light receiving element 10 and light emitting element 20 are electrically isolated from each other by a groove 50 formed in the Si substrate 11. The light receiving element 10 is a phototransistor comprising a collector region (Si substrate 11), a base region 12, and an emitter region 13. The light emitting element 20 comprises an n-type GaN layer 21, an MQW layer 22, and a p-type GaN layer 23. A light receiving surface of the light receiving element 10 is formed in the Si substrate 11, and a light emitting surface of the light emitting element 20 is formed in a semiconductor layer formed on the Si substrate 11, so that the light receiving surface and light emitting surface are different in height.

Description

  The present invention relates to a structure of an optical coupling device including a light emitting element and a light receiving element formed on the same substrate, and a method for manufacturing the same.

  An optical coupling device (photocoupler) is used to transmit a signal using light in an electrically isolated system, and includes a light emitting element that emits an optical signal and a light receiving element that receives the optical signal. The Here, normally, a phototransistor made of silicon (Si) is used as the light receiving element. On the other hand, since it is difficult to form a light emitting element with Si, a light emitting diode composed of a pn junction made of a III-V group compound semiconductor is used as the light emitting element. For this reason, an optical coupling device in which these two elements (chips) manufactured separately are enclosed in the same package is widely used. Note that the light emitting element and the light receiving element are coupled by an optical signal, but are electrically insulated.

  In order to reduce the size and cost of the optical coupling device as a whole, the light emitting element and the light receiving element are made into one chip, that is, they are not manufactured separately but manufactured on the same substrate. It is effective. An example of this configuration is described in Patent Document 1. In this configuration, a recess is formed in a semiconductor substrate, and a semiconductor layer is epitaxially grown therein. A light emitting element and a light receiving element are formed in the left and right regions of the semiconductor layer, respectively, separated by a groove, and the groove is filled with a translucent resin material. Thus, the formed light emitting element and light receiving element are electrically separated by the groove, and light emitted by the light emitting element reaches the light receiving element through the groove (translucent resin material).

  A similar configuration is also described in Patent Document 2. In this configuration, a light emitting element and a light receiving element are formed on a semiconductor layer epitaxially grown on a Si substrate, and the Si substrate is attached to an insulating substrate. Thereafter, a groove penetrating the Si substrate is formed between the light emitting element and the light receiving element, and the groove is filled with a translucent resin. As a result, similarly to Patent Document 1, it is possible to realize a configuration in which the light receiving element can receive light from the light emitting element and the light emitting element and the light receiving element are electrically separated by the groove.

  By using such a configuration, a one-chip optical coupling device can be obtained.

JP-A-6-5906 JP 2006-351859 A

  In any of the above manufacturing methods, the light emitting element and the light receiving element are formed of the same semiconductor layer formed by epitaxial growth on the semiconductor substrate. Formed.

  Here, the light emitting part in the light emitting element is limited to the vicinity of the pn junction interface, and the light is emitted strongly in the direction perpendicular to the interface, and weakened in the direction parallel to the interface. That is, this pn junction interface can be considered as a light emitting surface. Here, when the light-emitting element and the light-receiving element are formed at substantially the same height, the light-receiving element is positioned in a direction in which the intensity of the emitted light decreases as viewed from the light-emitting surface. Therefore, the rate at which the emitted light reaches the light receiving element from the light emitting surface is reduced, and the utilization efficiency of the emitted light in the optical coupling device is reduced. Alternatively, when the emission intensity is weak, the light receiving element cannot detect this emission.

  As described above, it is difficult to increase the utilization efficiency of the emitted light in the one-chip optical coupling device.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The optical coupling device of the present invention is an optical coupling device in which an electrically isolated light receiving element and a light emitting element are formed in a light receiving element region and a light emitting element region in a semiconductor substrate, respectively, A light-receiving element formed by a diffusion layer in a semiconductor substrate, and a semiconductor formed on one main surface of the semiconductor substrate in the light-emitting element region different from the light-receiving element region on one main surface of the semiconductor substrate Between the light emitting element formed by the layer, the insulating substrate bonded to the other main surface of the semiconductor substrate, and the light emitting element and the light receiving element, from the one main surface side to the other main surface And a groove penetrating the semiconductor substrate to the side.
The optical coupling device of the present invention is characterized in that a first reflective layer is formed on the light emitting element.
In the optical coupling device of the present invention, the semiconductor substrate is a conductive silicon single crystal, the light receiving element has a conductivity type opposite to that of the semiconductor substrate, a base diffusion layer formed in the semiconductor substrate, and the semiconductor An emitter diffusion layer having the same conductivity type as that of the substrate and formed in the base diffusion layer, wherein the semiconductor substrate operates as a collector diffusion layer.
In the optical coupling device of the present invention, the semiconductor layer is made of a compound semiconductor material containing at least one of N, As, P, or O as a constituent element and having a forbidden band width larger than that of the semiconductor substrate. It includes an n-type semiconductor layer and a p-type semiconductor layer made of a material.
The optical coupling device of the present invention is characterized in that the groove is filled with an insulating material.
The optical coupling device of the present invention includes a light guide layer made of a light-transmitting insulating material and covering the light emitting element and the light receiving element on one main surface of the semiconductor substrate.
The optical coupling device of the present invention includes a light guide layer made of a light-transmitting insulating material and covering the light emitting element and the light receiving element on one main surface of the semiconductor substrate and filling the groove. It is characterized by comprising.
The optical coupling device of the present invention includes a second reflective layer formed on the light guide layer.
The method for manufacturing an optical coupling device according to the present invention is an optical coupling device in which an electrically isolated light receiving element and a light emitting element are formed on one main surface side of a semiconductor substrate in the light receiving element region and the light emitting element region, respectively. A method of forming a light receiving element by forming a plurality of diffusion layers in the semiconductor substrate in the light receiving element region, and epitaxially growing the semiconductor layer on one main surface of the semiconductor substrate A light emitting element forming step of removing the semiconductor layer in a region other than the light emitting element region and forming a light emitting element in the semiconductor layer in the light emitting element region; and on the other main surface of the semiconductor substrate. Insulating substrate bonding step for bonding an insulating substrate, and between the light receiving element and the light emitting element, the semiconductor from the one main surface side to the other main surface side Characterized by comprising a groove forming step of forming a groove penetrating the plate, the.

  Since the present invention is configured as described above, the utilization efficiency of the emitted light can be increased in the one-chip optical coupling device.

It is the top view (a) of the optical coupling device which concerns on embodiment of this invention, and sectional drawing (b) in the AA direction. It is process sectional drawing which shows the manufacturing method of the optical coupling device which concerns on embodiment of this invention. It is sectional drawing which shows the modification of the optical coupling device which concerns on embodiment of this invention.

  Hereinafter, an optical coupling device and a manufacturing method thereof according to an embodiment of the present invention will be described. This optical coupling device is manufactured using a silicon (Si) substrate. In different regions on the Si substrate, the light receiving element is manufactured in the Si substrate, the light emitting element is manufactured on the Si substrate, and both are integrated into one chip. It has a configuration. At this time, the light receiving element (phototransistor) is constituted by a diffusion layer formed in the Si substrate (semiconductor substrate). The light-emitting element is composed of a semiconductor layer (GaN layer) formed by epitaxial growth on one main surface of the Si substrate, and a pn junction serving as a main light-emitting region is formed with a light-receiving element formed in the Si substrate. Are formed at different heights.

  FIG. 1A is a top view of the optical coupling device and FIG. 1B is a cross-sectional view in the AA direction. In this optical coupling device 1, the light receiving element 10 is formed in the light receiving element region B1, and one main surface (the upper surface in FIG. 1B) of the Si substrate (semiconductor substrate) 11 in the light emitting element region B2. The light emitting element 20 is formed thereon.

  An insulating substrate 40 is bonded to the other main surface (the lower surface in FIG. 1B) of the Si substrate 11 by an insulating adhesive 41. Further, the light receiving element 10 and the light emitting element 20 are electrically separated by a groove 50 formed in the Si substrate 11. The groove 50 is formed so as to penetrate the Si substrate 11 in the vertical direction in FIG. 1B, and has a shape extending in the vertical direction in FIG.

  The light receiving element 10 is a phototransistor including a collector region (Si substrate 11), a base region 12, and an emitter region 13. The base region 12 and the emitter region 13 are diffusion layers formed in the Si substrate 11 by impurity diffusion or ion implantation. In the light receiving element 10, the light receiving efficiency is highest on the lower surface of the base region 12 which is an interface between the base region 12 and the collector region (Si substrate 11). That is, this surface can be considered as a light receiving surface. Electrodes 31 and 32 are formed on the collector region (Si substrate 11) and the emitter region 13, respectively, so as to be electrically connected to these regions.

  The light emitting element 20 is a light emitting diode composed of a semiconductor layer formed by epitaxial growth on the Si substrate 11, and this semiconductor layer includes an n-type GaN layer (n-type semiconductor layer) 21 and an MQW (Multi Quantum Well) layer. 22 and a p-type GaN layer (p-type semiconductor layer) 23. Here, the MQW layer 22 has a structure in which, for example, a plurality of InGaN and GaN thin films having a thickness of several nanometers to several tens of nanometers are stacked, as described in, for example, Japanese Patent Application Laid-Open No. 2006-14813. In this configuration, the MQW layer 22 has the highest luminous efficiency. Since the MQW layer 22 is thin, this light emitting region can be considered to be planar. Light is emitted mainly from the light emitting surface in the vertical direction in FIG. For this reason, the emission intensity is high in the normal direction (vertical direction) of the light emitting surface, and low in the in-plane direction (horizontal direction) of the light emitting surface.

  A first reflective layer 24 is formed on the light-emitting element 20 (p-type GaN layer 22), and light emitted from the light-emitting element 20 to the upper side in FIG. 1B is the first reflective layer. 24 is reflected. In addition, electrodes 33 and 34 are formed on the first reflective layer 24 and the n-type GaN layer 21 in order to establish electrical connection with the p-type GaN layer 23 and the n-type GaN layer 21. The size of the p-type GaN layer 23 and the MQW layer 22 in the light emitting element 20 and the size of the base region 12 in the light receiving element 10 are each about 100 μm, for example.

  In the above configuration, the light receiving surface of the light receiving element 10 is formed in the Si substrate 11, and the light emitting surface of the light emitting element 20 is formed in the semiconductor layer formed on the Si substrate 11. Different height. Therefore, among the light emitted from the light emitting surface, the light emitted in the vertical direction in FIG. 1B is likely to reach the light receiving surface (light receiving element 10), and the proportion of the light reaching the light receiving surface is increased. Can do. That is, the utilization efficiency of emitted light can be increased.

  Further, a second reflective layer 52 is formed through a light-transmitting and insulating light guide layer 51 so as to cover the light receiving element 10 and the light emitting element 20. The light guide layer 51 serves as a light guide layer from the light emitting element 20 to the light receiving element 10. That is, light emitted from the light emitting element 10 is reflected by the first reflecting layer 24 and the second reflecting layer 52, propagates through the light guide layer 51, and reaches the light receiving element 10 (light receiving surface). That is, this structure can also increase the utilization efficiency of the emitted light.

  In the above structure, as shown in FIG. 1A, the opening of the light guide layer 51 on the electrode 33 and the electrode 34 are each rectangular. For this reason, wire bonding can be applied to the opening and the electrode 34, thereby making it possible to establish electrical connection with the p-type GaN layer 23 and the n-type GaN layer 21 in the light emitting element 20. . With this configuration, the light emitting element 20 can be driven.

  On the other hand, the electrode 32 connected to the emitter region 13 has a shape extending downward in FIG. 1A via an insulating layer on the Si substrate 11. Wire bonding is applied to the electrode 32 outside the range shown in FIG. The same applies to the electrode 31 connected to the collector region (Si substrate 11). As a result, the emitter region 13 and the collector region (Si substrate 11) can be electrically connected to each other. With this configuration, the light receiving element 10 can be operated.

  At this time, a groove 50 is formed between the light receiving element 10 and the light emitting element 20 (semiconductor layer), and the groove 50 is filled with the same translucent insulating material as that of the light guide layer 51. Thereby, the Si substrate 11 is divided at the light receiving element 10 side and the light emitting element 20 side, and the light receiving element 10 and the light emitting element 20 are electrically insulated. Therefore, the above structure can be used as an optical coupling device. The utilization efficiency of the emitted light in the optical coupling device 1 is increased as described above.

  FIG. 2 is a process cross-sectional view illustrating the method for manufacturing the optical coupling device 1. This section is the same section as FIG.

  First, as shown in FIG. 2A, a Si substrate (semiconductor substrate) 11 is prepared. The Si substrate 11 is a silicon single crystal substrate on which a phototransistor can be formed and a semiconductor layer made of GaN or the like can be heteroepitaxially grown thereon. The plane orientation is appropriately set so that high quality GaN or the like can be heteroepitaxially grown. Further, the Si substrate 11 shown in the drawing is doped as much as possible to be a collector region in the light receiving element (phototransistor), and has a predetermined conductivity type (n-type or p-type).

  Next, as shown in FIG. 2B, a base region 12 having a conductivity type opposite to the collector region (Si substrate 11) is formed in the region on the right side (light receiving element region) of the Si substrate 11 by impurity diffusion. Further, the emitter region 13 having the same conductivity type as that of the collector region is sequentially formed therein (light receiving element forming step). These processes are performed in the same manner as the manufacturing process of a normally known bipolar transistor, and can be performed, for example, by selective impurity diffusion using a silicon oxide film as a mask. As a result, a phototransistor including a collector region, a base region 12 and an emitter region 13 is formed in the Si substrate 11. Here, the photocurrent formed by the incidence of light becomes a base current, and the phototransistor is turned on and off. Therefore, the substantial light receiving portion (light receiving surface) in this phototransistor is a pn junction at the interface between the collector region (Si substrate 11) and the base region 12, which is mainly the lower surface of the base region 12.

  Next, as shown in FIG. 2 (c), a semiconductor layer is formed by epitaxial growth on one main surface (upper surface in the drawing) of the Si substrate 11 in the form shown in FIG. 2 (b). That is, an n-type GaN layer (n-type semiconductor layer) 21, an MQW layer 22, and a p-type GaN layer (p-type semiconductor layer) 23 are sequentially formed. This step can be performed by MBE (Molecular Beam Epitaxy) method or MOCVD (Metal Organic Chemical Vapor Deposition) method. The n-type GaN layer 21 is appropriately doped with an impurity serving as a donor, and the p-type GaN layer 23 is appropriately doped with an impurity serving as an acceptor. The thickness of the n-type GaN layer 21 can be set to, for example, 5.0 μm, and the thickness of the p-type GaN layer 23 can be set to, for example, about 0.2 μm. The MQW layer 22 has a structure in which a plurality of InGaN and GaN thin films having a thickness of several nm to several tens of nm, for example, are stacked. It is formed. In this epitaxial growth, since the surface of the Si substrate 11 serving as the substrate is flat, it is easy to obtain a high-quality n-type GaN layer 21, MQW layer 22, and p-type GaN layer 23 over the entire surface.

  Next, as shown in FIG. 2D, the n-type GaN layer 21, the MQW layer 22, and the p-type GaN layer 23 are respectively formed to form the light emitting element 20 (light emitting element forming step). This step is performed by forming a photoresist, a silicon oxide film or the like as a mask, and dry etching or wet etching these materials in a region other than the region where the mask is formed. Further, as illustrated, the MQW layer 22 and the p-type GaN layer 23 are made smaller than the n-type GaN layer 21. As a result, the light emitting element 20 including the semiconductor layer (the n-type GaN layer 21, the MQW layer 22, and the p-type GaN layer 23) after forming is formed. Since the forbidden band width of GaN is larger than the forbidden band width of Si, the light receiving element 10 (phototransistor) can receive the light emitted from the light emitting element 20.

  Next, as shown in FIG. 2E, the first reflective layer 24 is formed on the surface (upper surface) of the p-type GaN layer 23. The first reflective layer 24 is made of a material that can make ohmic contact with the p-type GaN layer 23 and can reflect the light emitted from the MQW layer 22 serving as a light emitting region. For example, a metal material such as Al can be used as this material. In FIG. 2E, the first reflective layer 24 is formed over the entire surface of the p-type GaN layer 23, but it is not necessarily formed over the entire surface. As the formation method, the above metal material is formed on the entire surface, a mask such as a photoresist is formed at a desired location, and etching is performed to remove the metal material other than the desired location (etching method). (2) After forming a mask such as a photoresist other than the desired location, the above metal material is deposited on the entire surface, and then the metal material other than the desired location is removed by removing the mask (lift-off method) ) Can be used.

  Next, as shown in FIG. 2 (f), each of the Si substrate 11 (collector region), the emitter region 13, the first reflective layer 24, and the n-type GaN layer 21 is electrically connected to or The electrodes 31 to 34 are formed using materials that can form ohmic junctions. Although simplified here, in reality, materials that can be electrically or ohmic-bonded to each layer are different, so that the formation is performed separately. In any case, as the formation method, any one of the etching method and the lift-off method can be used.

  Thereafter, as shown in FIG. 2G, the insulating substrate 40 is bonded to the back surface (lower surface) of the Si substrate 11 using an insulating adhesive 41 (insulating substrate bonding step). The insulating substrate 40 is made of a material having sufficient mechanical strength and high insulating properties, such as alumina.

  Next, as shown in FIG. 2H, a groove 50 reaching the insulating substrate 40 from the upper side in the drawing is formed between the n-type GaN layer 21 (light emitting element 20) and the base region 12 (light receiving element 10). (Groove forming step). FIG. 1H shows a cross section perpendicular to the direction in which the groove 50 extends. This step is performed using, for example, a dicing saw. After this step, the Si substrate 11 is divided into right and left in the drawing by the groove 50, but since the insulating substrate 40 is bonded, it is easy to handle the structure shown in FIG. .

  Next, as shown in FIG. 2 (i), the trench 50 is buried, and the p-type GaN layer 23, the first reflective layer 24, the electrode 33, etc. (light emitting element 20), the base region 12, and the emitter region 13. The light guide layer 51 is formed so as to cover the electrodes 32 and the like (the light receiving element 10). As a material of the light guide layer 51, for example, a polyimide resin or the like which is a light-transmitting and insulating material (light-transmitting insulating material) and can fill the groove 50 can be used. In order to make the polyimide resin into this form, for example, a liquid polyimide resin may be applied and then cured, and then selectively etched using a mask as much as possible in the form of FIG. Here, an opening is provided on the electrode 33 on the first reflective layer 24 so that wire bonding can be performed later at this location.

  Thereafter, as shown in FIG. 2 (j), a second reflective layer 52 is formed on the light guide layer 51. As the second reflective layer 52, a material that reflects light can be used in the same manner as the first reflective layer 24. However, since the second reflective layer 52 and the semiconductor are not directly connected, ohmic properties are not required. . The patterning of the second reflective layer 52 can be performed by an etching method or a lift-off method, similarly to the first reflective layer 24.

  Thereby, the optical coupling device 1 having the configuration shown in FIG. 1 is manufactured. In practice, this structure is enclosed in a package, and wire bonding is applied to the second reflective layer 52 on the electrodes 31, 32, 34 or the electrode 33, and connected to each lead terminal in the package. The description is omitted.

  In this manufacturing method, after a plurality of diffusion layers to be the light receiving elements 10 are formed in the Si substrate 11 in advance, a semiconductor layer to be the light emitting elements 20 is formed on the Si substrate 11. Thereby, the optical coupling device 1 in which the light emitting surface of the light emitting element 20 and the light receiving surface of the light receiving element 10 have different heights can be easily obtained.

  In the above manufacturing process, the insulating substrate bonding process (FIG. 2G) is performed before the groove forming process and in other processes performed thereafter, the insulating substrate 40 and the insulating adhesive 41. Can be performed at a point different from the above, as long as does not adversely affect. For example, insulation is performed before any of the formation of the semiconductor layer (FIG. 2D), the formation of the first reflective layer (FIG. 2E), and the formation of the electrode (FIG. 2F) in the light emitting element formation step. It is also possible to perform a conductive substrate bonding step. In addition, the order of the steps in FIG. 2 can be appropriately changed as long as the structure of FIG. 1 can be formed and the characteristics of the light receiving element 10 and the light emitting element 20 are kept good.

  In the above example, the n-type GaN layer 21, the MQW layer 22, and the p-type GaN layer 23 are formed on the entire main surface of the Si substrate 11 by epitaxial growth (FIG. 2C), and then these layers are formed. Is set to be removed except for a desired portion (FIG. 2D). However, these layers can be selectively epitaxially grown on the Si substrate 11 in advance.

  In the above example, the MQW layer 22 is inserted between the n-type GaN layer 21 and the p-type GaN layer 23 in order to increase the luminous efficiency, but a normal pn junction in which the MQW layer 22 is not inserted is used. A light emitting diode may be used. Also in this case, the pn junction surface can be considered as the light emitting surface, and the light emitting surface is formed at a place higher than the light receiving surface, so that the above effect can be obtained in the same manner.

  As described above, the first reflective layer 24, the light guide layer 51, and the second reflective layer 52 further increase the use efficiency of the emitted light. Even when these are not used, the light emitting surface is used in the above configuration. It is clear that the efficiency of using the emitted light can be increased because the height of the light receiving surface is different from that of the light receiving surface. It is also clear that if the groove 50 is formed, the light emitting element 20 and the light receiving element 10 are electrically insulated even when the groove 50 is not filled with an insulating material. When these are not used, the above manufacturing method can be further simplified.

  Other configurations may be used for the light guide layer 51, the second reflective layer 52, and the like. FIG. 3 is a cross-sectional view of the optical coupling device 101 using the configuration of this example. Here, different materials are used for the insulating material filled in the groove 50 and the translucent insulating material that guides light from the light emitting element 20 to the light receiving element 10. Here, the MQW layer 22 is not used, and the light emitting element 20 is a light emitting diode using a simple pn junction.

  In FIG. 3, an insulating filling layer 53 is formed in the groove 50. As the material of the insulating filling layer 53, a material having a high insulating property and capable of filling the groove 50 is used. For example, a polyimide resin similar to the above can be used, but translucency is unnecessary. is there.

  On the other hand, the light guide layer 54 is not required to be filled as much as the material of the insulating filling layer 53, and a material having higher translucency can be used instead. Examples of such a material include silicon oxide and SOG (Spin-On Glass).

  That is, by using different materials for the groove filling layer 53 and the light guide layer 54, a material with higher insulation can be used in the former, and a material with higher translucency can be used in the latter. As a result, it is possible to increase the insulation between the light emitting element 20 and the light receiving element 10 and further increase the light utilization efficiency.

  In the above example, the Si substrate 11 is conductive and the Si substrate 11 itself is used as the collector region. However, the Si substrate may be non-doped and the collector region may be formed by impurity diffusion in the same manner as the base region 12 and the like. Good. Furthermore, in the above example, a phototransistor is used as the light receiving element 20, but the present invention is not limited to this as long as it can receive light emitted from the light emitting element and convert it into an electrical signal. For example, a photodiode having a pn junction can be used.

  Further, the configuration of each electrode connected to the light receiving element and the light emitting element is not limited to the configuration shown in FIG. 1 as long as it is electrically connected to the light receiving element and the light receiving element can receive light emitted from the light emitting element. Any configuration can be adopted.

  In the above example, the light receiving element 10 is formed in the Si substrate 11, and the light emitting element 20 is formed in the layer epitaxially grown thereon. A similar configuration can be formed even when a semiconductor substrate other than the Si substrate is used. At this time, by setting the forbidden band width of the light emitting element side to be equal to or larger than the forbidden band width of the material serving as the substrate, the light receiving element can receive light emitted from the light emitting element. Further, the material on the light emitting element side needs to be a material that can be epitaxially grown on the substrate and has high luminous efficiency. As an example of this, a GaAs substrate is used as a semiconductor substrate, a diode is formed therein as a light receiving element, and an n-type GaN layer and a p-type GaN layer are sequentially formed on the GaAs substrate to form a light emitting element (light emitting diode). be able to. As another case where such a condition is satisfied, for example, the above-described Si or GaAs can be used as the material of the semiconductor substrate. As a material of the light emitting element, a compound semiconductor containing at least one of N, As, P, or O as a constituent element, such as a III-V group compound semiconductor such as GaAs, GaP, or InP, or an oxide semiconductor such as ZnO. Materials can be used. However, by setting the forbidden band width of the compound semiconductor material to be equal to or larger than the forbidden band width of the semiconductor substrate material, the light receiving element can receive the emitted light. As such a III-V compound semiconductor, a GaN-based mixed crystal semiconductor or the like can also be used as a group III nitride semiconductor. As in the case of using GaAs, the semiconductor substrate and the semiconductor layer formed by epitaxial growth on the semiconductor substrate may be the same material.

  Further, in the above example, the insulating substrate 40 is bonded to the Si substrate (semiconductor substrate) 11 using the insulating adhesive 41, but after the insulating property between the light receiving element and the light emitting element forms the groove. As long as it can be ensured, the bonding method of the insulating substrate and the semiconductor substrate is arbitrary. For example, it is possible to manufacture an optical coupling device similar to the above using a semiconductor substrate previously formed on an insulating substrate.

1, 101 Optical coupling device 10 Light receiving element 11 Si substrate (semiconductor substrate)
12 Base region 13 Emitter region 20 Light receiving element (semiconductor layer)
21 n-type GaN layer (n-type semiconductor layer)
22 MQW (Multi Quantum Well) layer 23 p-type GaN layer (p-type semiconductor layer)
24 First reflective layers 31 to 34 Electrode 40 Insulating substrate 41 Insulating adhesive 50 Grooves 51 and 54 Light guide layer 52 Second reflective layer 53 Insulating filling layer

Claims (9)

An optical coupling device in which the electrically isolated light receiving element and the light emitting element are respectively formed in the light receiving element region and the light emitting element region in the semiconductor substrate,
In the light receiving element region, a light receiving element formed by a diffusion layer in the semiconductor substrate;
In the light emitting element region different from the light receiving element region on one main surface of the semiconductor substrate, a light emitting element formed by a semiconductor layer formed on one main surface of the semiconductor substrate;
An insulating substrate bonded to the other main surface of the semiconductor substrate;
Between the light emitting element and the light receiving element, a groove penetrating the semiconductor substrate from the one main surface side to the other main surface side;
An optical coupling device comprising:   The optical coupling device according to claim 1, wherein a first reflective layer is formed on the light emitting element. The semiconductor substrate is a conductive silicon single crystal,
The light receiving element is
A base diffusion layer having a conductivity type opposite to that of the semiconductor substrate and formed in the semiconductor substrate;
An emitter diffusion layer having the same conductivity type as the semiconductor substrate and formed in the base diffusion layer;
Comprising
The optical coupling device according to claim 1, wherein the semiconductor substrate operates as a collector diffusion layer. The semiconductor layer is
An n-type semiconductor layer and a p-type semiconductor layer made of a compound semiconductor material that includes at least one of N, As, P, or O as a constituent element and whose forbidden band width is larger than that of the semiconductor substrate; The optical coupling device according to claim 1, further comprising:   The optical coupling device according to any one of claims 1 to 4, wherein the groove is filled with an insulating material.   6. A light guide layer made of a light-transmitting insulating material and covering the light emitting element and the light receiving element on one main surface of the semiconductor substrate is provided. The optical coupling device according to Item.   A light guide layer made of a translucent insulating material is provided on one main surface of the semiconductor substrate so as to cover the light emitting element and the light receiving element and fill the groove. The optical coupling device according to any one of claims 1 to 4.   The optical coupling device according to claim 6, further comprising a second reflective layer formed on the light guide layer. A method of manufacturing an optical coupling device in which an electrically isolated light receiving element and a light emitting element are formed on one main surface side of a semiconductor substrate in the light receiving element region and the light emitting element region, respectively.
A light receiving element forming step of forming a light receiving element by forming a plurality of diffusion layers in the semiconductor substrate in the light receiving element region;
The semiconductor layer is formed on one main surface of the semiconductor substrate by epitaxial growth, and then the semiconductor layer in a region other than the light emitting device region is removed to form a light emitting device in the semiconductor layer in the light emitting device region An element formation process;
An insulating substrate bonding step of bonding an insulating substrate to the other main surface of the semiconductor substrate;
A groove forming step of forming a groove penetrating the semiconductor substrate from the one main surface side to the other main surface side between the light receiving element and the light emitting element;
An optical coupling device manufacturing method comprising:

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